JERUSALEM (JTA) — The United States Embassy in Jerusalem issued a security alert on Monday for U.S. citizens in Israel after the assassination of top Iranian general Qassem Soleimani prompted Iran to promise “harsh revenge.”

“Out of an abundance of caution, the Embassy strongly encourages U.S. citizens to remain vigilant and take appropriate steps to increase their security awareness, as security incidents, including rocket fire, often take place without warning,” the alert read.

Soleimani was the head of the Iranian Quds Force, which operates a number of regional militias and is allied with terrorist groups targeting Israel, including Hezbollah and Hamas.

Meanwhile, the head of the Israel Defense Forces Southern Command said on Monday that Israel is observing the escalation between the U.S. and Iran “from the sidelines,” distancing the Jewish state from a possible conflict.

“The assassination also has ramifications for us as Israelis, and we must follow it closely, but we aren’t the main story here — and it’s good that it happened far away,” Maj. Gen. Herzi Halevi said at a conference in Jerusalem sponsored by Ynet and the daily newspaper Yediot Acharonot.

He said that the IDF has so far not identified any attempts by the Palestinian Islamic Jihad, which receives Iranian military and financial support, to carry out attacks against Israel in response to the killing.